Gas Chromatography - Tandem Techniques - Modern GC/IR Systems > Thermogravimetric Analysis (TGA) Coupled with GC/IR and GC/MS > Page 57


The apparatus consisted of a Perkin Elmer Model 7 thermogravimetric analyzer coupled to a Hewlett-Packard GC/IR/MS system. A heated transfer line from the TGA to the gas chromatograph conveyed the pyrolysis products to the column and included a special injection device. The furnace was maintained at a pressure of 0.14 bar above atmospheric pressure, to force the decomposition gases and vapors through the conduit to the sampling device. The gasses vapors, produced during the thermogravimetric analysis are periodically sampled during the heating program. The components are separated on the capillary column and the column exit gas is split into two streams. One stream passes directly to the FTIR spectrometer and the other to the mass spectrometer. Thus, either a total ion current chromatogram and/or a total IR absorption chromatogram can be generated in real time. Alternatively, the chromatogram can be reconstructed after the analysis is complete. In addition, IR and MS spectra from any selected peak can be generated from disc for identification purposes. Identification can be achieved by direct comparison with reference spectra, or by elucidating the structure from the data provided by the complementary IR and MS spectra.



The Sampling Condition Normal Non-sampling Condition


Figure 46. Diagram of the Automatic Vapor Sampler